poplar vs wood

poplar and wood both are nouns.

Word	Noun	Adjective	Verb	Adverb
poplar	Yes	No	No	No
wood	Yes	No	No	No

As nouns, wood is a hypernym of poplar; that is, wood is a word with a broader meaning than poplar:

poplar (noun)	wood (noun)
any of numerous trees of north temperate regions having light soft wood and flowers borne in catkins	any wind instrument other than the brass instruments
soft light-colored non-durable wood of the poplar	a golf club with a long shaft used to hit long shots; originally made with a wooden head
	the trees and other plants in a large densely wooded area
	the hard fibrous lignified substance under the bark of trees